1. Field of the Invention
The present invention relates to a thin-film magnetic head equipped with an inductive type electromagnetic transducer, a head slider, a head gimbal assembly, a hard disk drive, and a method of making a thin-film magnetic head.
2. Related Background Art
As hard disk drive have been increasing their areal density, magnetic heads for perpendicular recording have been coming into reality. The perpendicular recording becomes more stable as bits are recorded at a higher density, and thus is superior to longitudinal (in-plane) recording in resistance to thermal fluctuation. In such a perpendicular recording scheme, it has been feared that information recorded in a recording medium may be erased by external magnetic fields. When information is recorded in a double layer recording medium including a soft magnetic foundation layer by using a so-called single-pole head, for example, external magnetic fluxes may concentrate directly under the magnetic pole, thereby erasing the information recorded in the recording medium.
For overcoming such a problem of erasing the recording, a thin-film magnetic head comprising a shield layer made of a soft magnetic material near a single magnetic pole has conventionally been proposed (The Magnetics Society of Japan, the 124th Topical Symposium Data pp. 9–15). FIG. 11 schematically shows an example of such a thin-film magnetic head. This thin-film magnetic head 100 comprises a reproducing head section 110 and a recording head section 130.
The reproducing head section 110 mainly comprises a lower shield layer 112 made of a soft magnetic material, an MR (Magneto Resistive) device 114 for reading out information, and an upper shield layer 116. On the other hand, the recording head section 130, which is a so-called inductive type electromagnetic transducer, mainly comprises an auxiliary magnetic pole layer 132, a gap layer 133 made of a nonmagnetic material, a main magnetic pole 134, a recording shield gap layer 135 made of a nonmagnetic material, and a recording shield layer 136 made of a soft magnetic material. The recording shield layer 136 can block external magnetic fields. The recording shield gap layer 135 is provided in order to separate the main magnetic pole 134 and the recording shield layer 136 from each other. After the upper face of the recording shield gap layer 135 is flattened by chemical mechanical polishing or the like, the recording shield layer 136 is formed.